The present invention relates to recovery of insoluble solids from a liquid mixture. As a particular example, the invention relates to methods for the selective recovery of valuable tartrate-containing solid material that settles, over time, to the bottom of a container of pressed grape juice or wine.
Techniques to separate and harvest valuable sub-components from liquid and from liquid-solid mixtures that contain varying proportions of soluble and insoluble solids have been under continuous development over many years. Methods for the clarification of these types of mixtures via natural sedimentation and separation of constituents without requiring agitation, centrifugation, or other application of force are appealing. However, practical problems to economically perform such separation of potentially valuable constituents from essentially worthless by-products remain.
For example, pressed fruit juices such as grape juice and other grape-based materials are typically, and undesirably, turbid or cloudy when first pressed. Such solid-liquid mixtures may be stored in tanks or other containers for long time periods so that they may settle for clarification and other purposes. A typical type of storage/settling tank, as is later described in detail, is fitted with a number of valved access ports located at different elevations. These access ports may be used to periodically draw samples for analyses. For example, samples may be drawn from the valved access ports on a weekly basis and analyzed to determine specific characteristics or properties present in the mixture at the corresponding levels within the tank. As mixture density will generally decrease with elevation, samples harvested from higher elevation ports will usually meet an accepted clarification level in a shorter storage time than the liquid that is closer to the bottom of the tank. As the mixture settles/clarifies over time, it may be drawn, as saleable product, from the tank via the upper valved access ports. Periodic analyses may eventually show no change in the measured characteristic (say, for example, volume percentage of insoluble solids or xe2x80x9cISSxe2x80x9d) at a particular level within the tank. At that time, that portion of the material below that level down to the bottom of the tank would be declared to be a xe2x80x9cbottom.xe2x80x9d The term xe2x80x9ctank bottomxe2x80x9d is, therefore, used to describe the mixture of juice/liquid and sediment existing at or near the bottom of a tank of settled liquid or juice. Tank bottoms are not suitable for the production of finished products due to the high proportion of mixture components that have settled by gravity to the bottom of the tank or storage container.
xe2x80x9cFilter trimxe2x80x9d is generated as a resultant by-product during the process of recovering saleable/clarified grape juice from tank bottoms. Filter trim describes the solid material that is separated out of the mixture or xe2x80x9ctank bottom.xe2x80x9d This is typically generated as a result of filtration, wherein diatomaceous earth (DE) may serve as a filtration aid. The DE is added to the liquid xe2x80x9ctank bottomsxe2x80x9d immediately prior to filtration and remains present in the xe2x80x9cfilter trimxe2x80x9d in varying proportions depending on when, during the recovery process, the material is collected. Whether the xe2x80x9cfilter trimxe2x80x9d is produced from single strength juice (herein denoted SS Bottoms) or comes from the processing of concentrate, it contains a significant amount of valuable tartrate precipitates. Excess argol (argol is, chemically, potassium bitartrate) separates from grape juice and wine precipitating in the form of crystals that gravitate to the bottom of the storage tank. These crystals are valuable as precursors for the production of cream of tartar, tartaric acid and other chemicals. This phenomenon is well known and was described, for example, in Reissued U.S. Pat. No. 14,636 to Welch, reissue date of Apr. 15, 1919. Screening and centrifugation techniques are therein described as typical argol recovery techniques. SS Bottoms are very inhomogeneous. Other insoluble solids, including bits of grape pulp and skin that remained after the pressing process, also may gravitate to the bottom of the storage tank. In this state, the aggregated, settled xe2x80x9ctank bottomxe2x80x9d material is not suitable for bottling and sale. The juice contained in the xe2x80x9cStank bottomsxe2x80x9d should be recovered for use in the production of finished products; the xe2x80x9cfilter trimxe2x80x9d portion should also be recovered with the DE and insoluble plant material effectively separated from the valuable argol.
Referring now to FIG. 1, tank 10 has valved access ports 11-15 with associated valves 111-115. Following settling/clarification, clarified juice, or other saleable liquids, may be drawn out of the tank at levels above the xe2x80x9ctank bottom,xe2x80x9d shown as 100. Such drawing might occur by, per FIG. 1, siphoning out liquid through access port 13. Then, an operator desiring to clean out tank 10, filter the tank bottom 100, recover the juice therein and, thereby, also collect filter trim connects a pump 17 directly to a gutter valve 116 associated with gutter port 16 located at the bottom of storage tank 10. Activating pump 17 leads to a single step recovery of an entire tank bottom 100. Diatomaceous earth is added at unit 18 along fluid path, F. The juice separated at unit 19 is recovered along fluid path 192. The resulting solids (filter trim) separated at unit 19 are recovered along solids path 191. For single strength grape juice processing, for example, the consistency of SS Bottoms is that of a thick, free-flowing liquid that may contain anywhere from about 1% to about 15%, or more, insoluble solids (ISS). The ISS in SS Bottoms contains tartrates (also called argol) as well as a significant percentage of other insoluble plant material (particles of pulp, skin, etc.). Tartrates are crystalline and are heavier than the insoluble plant material. The non-homogeneous nature of SS Bottoms is such that the heavier ISS (tartrates) will tend to settle closer to the bottom of a tank 10 than the lighter ISS plant material. Using the above harvesting method via gutter port 16, suction caused by pump 17 inevitably creates a channel through the thickest/most dense material residing at the bottom of the tank 10. As a result, the lighter material near the top liquid surface may easily be pumped out through this channel and down fluid path F before much of the heavier material residing at the bottom of the tank 10 is extracted. Therefore, at flow onset, relatively little of the heavier tartrate-containing material is harvested before it becomes diluted, both in density and in economic value. As a result, it is difficult to ascertain when the tartrate content of the filter trim is high enough to make the collection and sale of the filter trim economically desirable.
In accordance with an embodiment, a method for recovery of tartrate-containing, insoluble solids from an essentially settled grape-based mixture is provided. The mixture is housed in a container having a sidewall, a bottom, a vertical axis, a valved gutter port capable of providing access to container contents through the bottom, and a plurality of valved access ports capable of providing access to container contents through the sidewall. The access ports are disposed upon the sidewall at heights defined as distances from the bottom measured along the vertical axis. A siphoning port is chosen from among the plurality of valved access ports. A first pumping system is attached to the siphoning port. A siphoning port valve is opened to provide fluid communication between container contents resident essentially above a siphoning height and the first pumping system through the sidewall. The first pumping system is activated and a first container contents portion resident essentially above the siphoning height is extracted. A second pumping system is then attached to the valved gutter port, the second pumping system having a conduit permitting samples of an extracted second container contents portion to be analyzed outside of the container. A gutter port valve is opened to provide fluid communication between container contents and the second pumping system through the bottom. The second pumping system is activated and data is generated over time regarding the extracted second container contents portion being collected. It is ascertained when to begin recovery of the desired insoluble solids, when to begin recovery determined to be when data generated indicates that the extracted second container contents portion is, essentially, tartrate-containing material.
Choosing a siphoning port may further include sampling container contents extracted from specific access ports to generate sampling data; and analyzing the sampling data in order to designate one of the plurality of access ports as the siphoning port. Sampling may further comprise determining a volume percentage of insoluble solids as sampling data. Analyzing may further comprise comparing volume percentages of insoluble solids obtained from ports so as to select the siphoning port as the port from which extracted container contents equals a lowest percentage, the lowest percentage defined to be a lowest percentage in excess of a predetermined volume percentage of insoluble solids. The predetermined volume percentage of insoluble solids may, in an embodiment, be, approximately, one volume percent. Generation of data may be obtained by subjecting extracted second container contents to titration. Ascertaining when to begin recovery may be achieved when the extracted second container contents portion is, essentially, tartrate-containing material. This may occur when data generated from titration indicates no less than 2.0% citric acid by weight.
In another embodiment, a method for recovery of insoluble solids from an essentially settled mixture is provided. The solids have a predetermined characteristic. The mixture is housed in a container having a sidewall, a bottom, a vertical axis, a valved gutter port capable of providing access to container contents through the bottom, and a plurality of valved access ports capable of providing access to container contents through the sidewall. The access ports are disposed upon the sidewall at heights defined as distances from the bottom measured along the vertical axis, The method includes choosing a siphoning port from among the plurality of valved access ports. A first pumping system is attached to the siphoning port. A siphoning port valve is opened to provide fluid communication between container contents resident essentially above a siphoning height and the first pumping system through the sidewall. The first pumping system is activated. A first container contents portion resident essentially above the siphoning height is extracted. A second pumping system is attached to the valved gutter port. The second pumping system has a conduit permitting samples of an extracted second container contents portion to be analyzed outside of the container. A gutter port valve is opened to provide fluid communication between container contents and the second pumping system through the bottom. The second pumping system is activated. Data is generated over time regarding the extracted second container contents portion being collected, the data correlatable with the predetermined characteristic. When to begin recovery is ascertained and is, determined to be when data generated indicates that the extracted second container contents portion has the predetermined characteristic. The insoluble solids are then recovered.
In yet another embodiment, a method for recovery of tartrate-containing, insoluble solids from tank bottoms is provided. The tank bottoms are housed in a container having a valved port. A collection system is attached to the valved port. The collection system has a conduit permitting samples of tank bottoms to be analyzed and at least one receptacle capable of collecting recovered solids.The valved port is opened. A proxy analysis is performed on samples of tank bottoms retrieved from the conduit The data generated as part of the proxy analysis is known to be correlatable with tartrate content of the samples. When to begin tartrate recovery is ascertained based upon results obtained from the proxy analysis. Recovered tartrate-containing insoluble solids are directed to the at least one receptacle.